Fast4525

I want to add power to my '88 turbo S and the Lindsey 944 TURBO INSTANT RWHP PACK appears to be the best and easiest way to do it.

I like the idea of removing the KLR-controlled cycling valve but I worry about engine safety. Obviously I would limit the peak boost to around 17psi on 93 octane.

The way I understand it, the KLR + cycling valve limit boost pressure at part throttle but with an adjustable MBC it is possible to hit full boost at part thorttle.

If the DME chips are only mapped for TPS vs RPM it won't be able to compensate for the added boost and I fear that there could be too much timing advance and not enough fuel!!!

Am I on the right track with my thinking or am I totally crazy

Thoughts?

P.S. The original airbox and air intake snokel tube looks like a terrible design! Talk about a convoluted air path! Has anyone measured increased performance (throttle response, lag, power, etc) by installing an open K&N cone filter kit onto the AFM like the one Lindsey sells?

Richgreenster

If you are going to set your cars boost pressure to 17 psi and leave it alone (Ya Right! LOL) then the Lindsey Racing kits work great. But if you are going to keep modifying your car and keep adjusting the boost pressure then spend the extra money and go with Vitesse.

As far as the stock intake on the turbo, It is very restrictive but it can be opened up some but not as much as the MAF kits.

Fast4525

Is this beacuse Vitesse offers some type of piggyback computer that is user programmable for different parts combos?


What gains have users seen when using the large K&N cone mounted on the original AFM?

Auto_Werks 3.6

Don't over complicate this... You are on the right track realizing that you need to change the chips when going away from factory boost settings. Lots of guys run a Lindsey chip (MAX 951) with manual boost control without issue. Vitesse stuff is known for being some of the best on the market, but the cost will be significantly higher than chips, fuel pressure regulator, and an MBC from LR. If your budget is only around $300 I would go lindsey, if you know you want to go crazy later, get the full MAF kit from Vitesse. I can tell you that the inital 17 psi with stock AFM should be enough to put a smile on your face, but it will eventually get old. Everything eventually gets old... When have you actually reached enough power???

I never had any trouble with part throttle ignition with the MBC and MAX 951 chips. At low throttle settings, you are still at low load as the throttle plate is mostly closed. Sure the intake is pressurized, but since the airflow is choked off at the throttle, the air flow meter should not be pegged and should still provede accurate information for proper fueling. I doubt you'll develop full boost until 60% throttle or so, and that should be close to getting into WOT maps anyway... depending on how Mr. Berry has things setup.

PS the air intake is a bit of a hot topic... a bee hive to strike at if you will. The factory setup is not very straight, but it pulls in cooler dense air from the wheel well.

toddk911

I used, a long time ago, a K&N on the stock AFM and noticed little to no as the filter/snorkel is not really the restriction but the AFM "barn door".

Do some searching on AFM and MAF, etc. on the forum and you will get days worth of reading.

The least restrictive and coolest intake is a some mounting of an intake pipe behind the headlight right at the hole in the fender for cool air to a MAF.

In my case just adding a means of getting air directly from that fender hole made surface temp of the intake IC pipe noticably cooler before/after especially in cool ambient temps. The "butt dyno" was very noticable even over the MAF with just adding a 3" pipe from fender to my MAF.

On a cold day after WOT runs at 19-20psi my intake IC pipe will be just about as cold to the touch as the outside sheet metal.

Like Ryan said, it is not just more air, but more COOLER air where you see gains.

TurboTommy

fast 4525;
I think you're totally on the right track with your thinking, and I've often thought the same thing: With a manual boost controller, the potential boost curve vs throttle position is quite a bit different than the stock configuration.
So, a few things to consider:
Firstly, that's one reason I'm not a fan of a manual boost controller. I'd rather use the LBE which sort of like sets the initial boost gain and then the cycling valve takes over. This almost feels like a manual boost controller, but is safer for the engine if you set the LBE at reasonable levels.
Secondly, most newer chip guys probably have to assume that operators will have an aggressive boost rise vs throttle position, and they even endorse MBCs and different wastegates, etc. Therefore their timing and fuelling would be mapped accordingly. I definitely wouldn't use a MBC with the older weltmeister chips, for example.
Thirdly: You mentioned the DME using TPS and RPM; but the DME also uses a third very important piece of info. That is the actual air flow signal, whether it comes from the stock AFM or a MAF. For example you could have a relatively low TPS signal, but if the air flow signal is strong (to create the extra boost at that throttle position), it will be part of the equation for the chip in the DME to compensate.

At one time I also used a cone filter directly on the AFM. My experience was that it definitely gained in throttle response and low boost power; but full power was reduced because the ability for the turbo to "grab" the less restricted air did not make up for the loss because of excess heat the turbo sees.

Fast4525

Thanks Tommy. At least I am not going crazy

I suppose asking "who makes the best chips for a Turbo S" would just start up a huge war Perhaps I should ask if there are any chip company to avoid?

Rogue_Ant

Having looked at the Welt chip, I would be completely comfortable with using is w/ MBC... The timing curve is not that aggressive.

Close. The DME never knows actual TPS angle. It only knows the Idle switch, and WOT (signal from the KLR). So the DME understands three different situations: Idle, WOT, and if it isn't in either of those - it assumes it is in Part Throttle.
You are correct about using the airflow signal. In-fact, the DME relies very heavily on it, as the first fundamental calculation done is simply Airflow * RPM.


-Rogue

TurboTommy

Hmmm, interesting; that would certainly explain alot.
One thing though: you often see DME timing and fueling charts where, I believe, the horizontal axis indicates throttle opening percentages.

Rogue_Ant

No - the horizontal axis is a % of the DME's internal load calculation...
Check out the wiring diagram - you will see that there is no TPS angle/voltage signal going to the DME:

Auto_Werks 3.6

There are systems out there that only reference TPS, RPM, and air temp...they are the baby brother to speed density systems. Speed density would be like Danno's old manifold absolute pressure setups. EFI that only conciders throttle position and RPM are refered to as Alpha N, which may be how my 911's EFI is setup. I should find out this weekend, as I finally got a data cable. Either way the serious drawback to speed density system is that any change to the volumetric effeciency requires a change in the VE table on the PROM. Change your cam, change your chip... change your heads, change your chip..... piston rings wear out over time, change your chip. To some extent you guys run into that with these cars, but the theory behind MAF technology is that you don't have to change the programming as long as you dont draw more air than the MAF sensor can handle. That's where vitesse's "true maf code" pays off, allowing you to make some changes without throwing off the tune.